1. Field of the Invention
The present invention relates to a pellicle mounting fixture and specifically to a fixture for accurately positioning a mask adjacent to a pellicle so that the pellicle may be adhesively affixed to the mask.
2. Description of the Prior Art
A pellicle, in the form of a thin transparent membrane, is used in the semi-conductor industry to protect the surface of a photographic mask. The masks are used as part of the process of producing various semi-conductor devices such as integrated circuits. If any dust or particles fall onto the surface of the mask this will produce an inaccurate reproduction from the mask including spots representing the dust or particles. Therefore, in order to protect the mask from dust or other particles, a thin transparent membrane is positioned adjacent to and spaced from the mask so that any dust or other particles will fall onto the membrane rather than the mask. Since the dust or other particles and now maintained at a position spaced from the mask, the dust and other particles will be out of focus when the mask is used in the process of producing semi-conductor devices.
The pellicles of the prior art are generally formed with a frame member supporting the thin transparent membrane, and with the frame member attached to the mask by an adhesive so that the membrane is maintained in a fixed spaced relationship with the mask. If desired, pellicles may be affixed on both sides of the mask or may be affixed only on a single side of the mask.
In the prior art, the pellicles have usually been affixed either manually or by using very simple pin fixtures to guide the pellicle and mask toward each other. In either case, the placement of the pellicle is not accurately repeatable and the pressure used to affix the pellicle to the mask can vary widely. In addition, the prior art methods and structures do not provide for easy adaptability for different size pellicles or different size masks so that the prior art structures are generally not reliable in use.